1. Field of the Invention
The present invention relates to a vehicle door latch unit, and in particular, to a driving device of the latch unit.
2. Description of the Related Art
A conventionally well known latch unit includes a latch that engages with a striker and a ratchet that engages with the lath and holds the engagement between the latch and the striker, and in the latch unit, a driving device (a device having an automatic closing function, hereinafter also referred to as “automatic closing mechanism”) that rotates the latch by a motor power from a half latch position to a full latch position is associatively connected to the latch, and a driving device (a device having an automatic releasing function, hereinafter also referred to as “automatic releasing mechanism”) that rotates the ratchet by a motor power in a door opening direction (a direction in which the engagement with the latch is released) to bring a door into an openable state is associatively connected to the ratchet (for example, see Japanese Patent Application Laid-open No. 2014-009477, and see Japanese Patent Application Laid-open No. 2005-248485 for a latch unit including an automatic closing mechanism).
For control of the driving devices, signals from a plurality of switches are used. The plurality of switches are broadly classified into a driven side switch group that detects states (positions) of the latch and ratchet of the latch unit and a driving side switch group that detects a state (position) of a driving mechanism that rotates the latch and ratchet by a motor power.
A latch switch that detects an unlatch position, a half latch position, a full latch position, and the like of the latch and a ratchet switch that detects, for example, whether or not the ratchet has rotated to a position where the ratchet is able to engage with the latch correspond to the driven side switch group. A gear switch or the like that detects, for example, whether the driving mechanism, such as a sector gear, which is rotated by the motor power, is at a neutral position (initial position) or at an operation completion position corresponds to the driving side switch group.
Types and the numbers of the plurality of switches that are used vary, and methods of processing the signals from the plurality of switches also vary, depending on design concepts of the latch unit/driving mechanism, and in any case, durability of the switches and downsizing the cam body for turning the switches ON or OFF have been ongoing problems in the designing.